How to know what kind of alcohol a compound is? Primary, secondary or tertiary?

In a primary alcohol, the carbon atom attached to the -OH group is also attached to ONE ALKYL GROUP only. For example, CH₃-CH₂-CH₂-OH is a primary alcohol.

In a secondary alcohol, the carbon atom attached to the -OH group is also attached to TWO ALKYL GROUPS. For example, CH₃-CH(CH₃)-OH is a secondary alcohol.

In a tertiary alcohol, the carbon atom attached to the -OH group is also attached to THREE ALKYL GROUPS. For example, (CH₃)₃C-OH is a tertiary alcohol.

If the -OH is attached to a carbon on the end, it is a primary alcohol
If the -OH is attached to a C that is attached to 2 other C atoms, it is a secondary alcohol.
If the -OH is attached to a C that is attached to 3 other C atoms, it is a tertiary alcohol.

You must start with the structure of the alcohol. Look at the carbon atom to which the alcohol functional group (-OH) is attached. How many carbon atoms are attached to this alcoholic carbon? If the answer is one, then it's a primary alcohol. If the answer is two, it's a secondary alcohol. If the answer is three, it's a tertiary alcohol.